Replace long sequences of popq with a Drop(int) macro instruction.

vm/assembler_x64.cc

Index: vm/assembler_x64.cc
===================================================================
--- vm/assembler_x64.cc	(revision 7659)
+++ vm/assembler_x64.cc	(working copy)
@@ -1266,6 +1266,13 @@
 }
 
 
+void Assembler::Drop(int stack_elements) {
+  if (stack_elements > 0) {
+    addq(RSP, Immediate(stack_elements * kWordSize));

[srdjan, 2012/05/15 19:52:27]

When is an addq better than pop? Maybe add a TODO(fschneider)?

[Florian Schneider, 2012/05/15 21:40:56]

Not sure what is considered better: For i<4 pop is smaller, but always involves
a memory operation, whereas addq is only an ALU operation.

+  }

[srdjan, 2012/05/15 19:52:27]

ASSERT stack_elements >= 0?

[Florian Schneider, 2012/05/15 21:40:56]

Done.

+}
+
+
 void Assembler::LoadObject(Register dst, const Object& object) {
   if (object.IsSmi()) {
     movq(dst, Immediate(reinterpret_cast<int64_t>(object.raw())));